Welding Temperature Field Simulation On Square-rectangular Tube

This study uses the Q345D square rectangular tube as the object, which the specifications are F200×6.3mm. The temperatures of characteristic points in the cooling process are measured by the Infrared thermo-scope. Heat transfer coefficient is considered from three parts—air-cooling, contact heat transmitting and water spray cooling. Modificatory coefficients about heat transfer coefficient and the inner heat ascend is concluded by hand with plant model. The data is used as initial value in calculating modificatory coefficients with 3-Dmodel by means of finite element analysis software ANSYS. By orthogonal analysis, the precise Modificatory coefficients is obtained, so heat transfer coefficient and inner heat ascend can be calculated. The high frequency wilding temperature field is simulated by ANSYS, and then the paper analyzes the influence of welding process on microstructure in weld and nearby.The results indicate that the simulated temperatures of characteristic points agree with experiment data, so the model is much closed to actual situation. Thermal cycling curve of characteristic points and isothermal line on the cross section display that change in temperatures of weld is the most acute. Temperature in the top surface is little higher than the lower surface and isothermal line on the cross section is dipped, so temperature distribution of base metal is uniform. By companion with metallographic photos, abnormal structure forms in weld and overheated zone. It has influents on the Mechanical Properties of the welded tube, so it needs to be further improved by heat treatment.